In medical diagnostics, in particular, numerous disposable items are known, which have to be encoded rapidly, reliably and cost-effectively. Thus, by way of example, the examination of blood samples or other samples of body fluid, for example interstitial fluid, in clinical diagnostics enables early and reliable identification of pathological states and also targeted and astute monitoring of body states. Medical diagnostics generally presupposes that a sample of blood of interstitial fluid is obtained from the patient to be examined. For this purpose, the skin is usually perforated, for example at the finger pad or the ear lobe, with the aid of a sterile, pointed or sharp lancet in order thus to obtain a small amount of blood for analysis.
Self-monitoring of blood sugar levels is a method of diabetes control that is nowadays applied worldwide. Blood sugar devices in the prior art generally have an analysis instrument which interacts with at least one test element. The sample to be analyzed is applied to a test field of the test element and reacts in the test field with one or more reagents, if appropriate, which are generally chosen in a manner specific to the analyte to be detected. This reaction can be detected, for example optically and/or electrochemically.
In principle, the invention described below can be applied, for example, to all types of test elements in accordance with the prior art. Thus, the test element can comprise, for example, one or more of the following test elements: a test strip, in particular an individual test strip with an individual analysis zone or a plurality of analysis zones; a test tape; a test wheel with a plurality of analysis zones arranged circumferentially; a test wheel with a plurality of analysis zones arranged on its surface, in particular analysis zones arranged in a cake-slice shape; a foldable test element with a plurality of analysis zones (fan folding). In this case, by way of example, it is possible to use test elements in which the sample is applied directly to the analysis zone, for example by direct dropping, dabbing or the like. This direct application can be effected in the form of “top dosing”, for example, in which the analysis zone is arranged for example on a planar surface of the test element and the sample is applied to it from above. Alternatively or additionally, however, so-called “edge dosing” could also be considered, in which the sample is applied to an end or side face of the test element. In the case of edge dosing, by way of example, the sample can be applied directly to the analysis zones, or the sample can be transported from the application location to the analysis zone, for example by means of capillary forces. Further embodiments are conceivable. There is also a multiplicity of possibilities regarding the type of detection of the analyte. Thus, by way of example, electrochemical detection can be effected. Alternatively or additionally, optical detection can be effected. In the latter case, by way of example, direct optical detection can be effected by light being radiated in. Alternatively or additionally, the incident light or the light emerging from the analysis zone can also be transported by means of one or more optical waveguides. Various other embodiments are conceivable.
When such medical or diagnostic consumable materials such as test elements and/or lancets, for example, are used, a number of technical problems arise in practice, however, which in many cases have to be overcome by complex apparatus solutions. Thus, one difficulty consists in the fact that different test elements which can be used in an analysis system can have differences among one another. Thus, by way of example, differences can arise with regard to the manufacturer and/or the production method, with regard to the detection reagents used, with regard to the analyte to be detected, with regard to the analysis method and/or analysis system to be used, with regard to the conditions under which the analysis is intended to be carried out, with regard to the parameters and/or the algorithms for the evaluation of measurements, with regard to the batch numbers, with regard to batch-specific special features, with regard to the manufacturing method, with regard to the number of analysis zones on a test element or the like. In the case of lancets or other types of medical disposable items, too, such item-specific information components can arise, in particular information components with regard to the manufacturer, the type of lancet, the lancet systems to be used or the like. In the following application, such information components are generally encompassed by the expression “item-specific information components”, wherein such item-specific information components generally relate to information components concerning the medical disposable items, which can differ from item to item or even within an item (for example from analysis zone to analysis zone in the case of test elements having a plurality of analysis zones).
In many cases it is necessary, therefore, to correspondingly encode a medical disposable item or a group of medical disposable items, for example medical disposable items accommodated in a magazine, in order, as soon as this is necessary, to be able to provide these item-specific information components accordingly. One important exemplary application consists in automatic reading-in of item-specific information components by an analysis instrument which is intended to use medical disposable items such as, for example, test strips, test tapes or lancets.
Since manual inputting and read-out of such item-specific information components are generally unreasonable or inconvenient for the patient, various methods and systems in which item-specific information components can be read in automatically are known from the prior art. Thus, by way of example, systems are known in which firstly a calibration test element has to be introduced into the analysis system. Systems are also known in which a separate evaluation code is provided on individual test elements, which code is read by a separate read-out unit. For examples of methods and systems for coding item-specific information components, see US 2007/0273928 A1 and U.S. Pat. No. 5,281,395, the disclosures of which are hereby incorporated herein by reference in their entireties.
In addition to such code systems for individual test strips, different types of codings themselves for encoding test tapes are also known. For example, it is known to provide a coding region on a test tape at the beginning of the test tape, the coding region comprising at least one information component. The coding region can be read for example by the detector which is also used for the optical measurement. Strip bar codes or bar codes in the form of two-dimensional black-white test fields may be used for encoding purposes, for example. Such one- or two-dimensional bar codes are known in various embodiments and in accordance with various standards. The bar codes can be detected, for example, in the form of black-white identification by means of different gray-scale values. Examples of different codings are described in U.S. Pat. No. 5,077,010 and DE 101 23 406 A1, the disclosures of which are hereby incorporated herein by reference in their entireties.
The problem of conventional bar codes is, however, that generally they have to comprise not just a simple serial number, rather many item-specific information components have a more extensive storage depth. Thus, by way of example, extensive information components generally have to be provided for test strips or test tapes in order to enable correct and reliable evaluation of these test elements.
It is therefore known also to use, in addition to simple black-white information components, halftones or gray-scale values themselves as information carrier. Thus, by way of example, an encoding system is known in which data in an image are encrypted by using halftone settings. E.g., see WO 03/086759 A1, the disclosure of which is hereby incorporated herein by reference in its entirety. However, these known methods are comparatively complex and in many cases require an implementation that is costly in respect of resources. Such complexity and outlay often cannot be realized in the field of medical diagnostics, in which, in particular, simple and cost-effective handheld instruments often have to be provided.
It is therefore an object of the present invention to specify a method and a device which are suitable for the encoding and decoding of medical disposable items and which can be realized simply and cost-effectively, in conjunction with a sufficiently large amount of storable or encodable information.